package com.chaoshan.util;

/**
 * @DATE: 2022/05/18 23:07
 * @Author: 小爽帅到拖网速
 */
import com.chaoshan.config.SensitiveWordInitConfig;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

//敏感词过滤器：利用DFA算法  进行敏感词过滤
public class SensitiveFilter {
  //敏感词过滤器：利用DFA算法  进行敏感词过滤
  private Map sensitiveWordMap = null;

  // 最小匹配规则
  public static int minMatchType = 1;

  // 最大匹配规则
  public static int maxMatchType = 2;

  // 单例
  private static SensitiveFilter instance = null;

  // 构造函数，初始化敏感词库
  private SensitiveFilter() throws IOException {
    sensitiveWordMap = new SensitiveWordInitConfig().initKeyWord();
  }

  // 获取单例
  public static SensitiveFilter getInstance() throws IOException {
    if (null == instance) {
      instance = new SensitiveFilter();
    }
    return instance;
  }

  // 获取文字中的敏感词
  public Set<String> getSensitiveWord(String txt, int matchType) {
    Set<String> sensitiveWordList = new HashSet<String>();
    for (int i = 0; i < txt.length(); i++) {
      // 判断是否包含敏感字符
      int length = CheckSensitiveWord(txt, i, matchType);
      // 存在,加入list中
      if (length > 0) {
        sensitiveWordList.add(txt.substring(i, i + length));
        // 减1的原因，是因为for会自增
        i = i + length - 1;
      }
    }
    return sensitiveWordList;
  }
  // 替换敏感字字符
  public String replaceSensitiveWord(String txt, int matchType,
                                     String replaceChar) {
    String resultTxt = txt;
    // 获取所有的敏感词
    Set<String> set = getSensitiveWord(txt, matchType);
    Iterator<String> iterator = set.iterator();
    String word = null;
    String replaceString = null;
    while (iterator.hasNext()) {
      word = iterator.next();
      replaceString = getReplaceChars(replaceChar, word.length());
      resultTxt = resultTxt.replaceAll(word, replaceString);
    }
    return resultTxt;
  }

  /**
   * 获取替换字符串
   *
   * @param replaceChar
   * @param length
   * @return
   */
  private String getReplaceChars(String replaceChar, int length) {
    String resultReplace = replaceChar;
    for (int i = 1; i < length; i++) {
      resultReplace += replaceChar;
    }
    return resultReplace;
  }

  /**
   * 检查文字中是否包含敏感字符，检查规则如下：<br>
   * 如果存在，则返回敏感词字符的长度，不存在返回0
   * @param txt
   * @param beginIndex
   * @param matchType
   * @return
   */
  public int CheckSensitiveWord(String txt, int beginIndex, int matchType) {
    // 敏感词结束标识位：用于敏感词只有1位的情况
    boolean flag = false;
    // 匹配标识数默认为0
    int matchFlag = 0;
    Map nowMap = sensitiveWordMap;
    for (int i = beginIndex; i < txt.length(); i++) {
      char word = txt.charAt(i);
      // 获取指定key
      nowMap = (Map) nowMap.get(word);
      // 存在，则判断是否为最后一个
      if (nowMap != null) {
        // 找到相应key，匹配标识+1
        matchFlag++;
        // 如果为最后一个匹配规则,结束循环，返回匹配标识数
        if ("1".equals(nowMap.get("isEnd"))) {
          // 结束标志位为true
          flag = true;
          // 最小规则，直接返回,最大规则还需继续查找
          if (SensitiveFilter.minMatchType == matchType) {
            break;
          }
        }
      }
      // 不存在，直接返回
      else {
        break;
      }
    }

    if (SensitiveFilter.maxMatchType == matchType){
      if(matchFlag < 2 || !flag){        //长度必须大于等于1，为词
        matchFlag = 0;
      }
    }
    if (SensitiveFilter.minMatchType == matchType){
      if(matchFlag < 2 && !flag){        //长度必须大于等于1，为词
        matchFlag = 0;
      }
    }
    return matchFlag;
  }
}
